Acuteness of mental discernment, soundness of judgment. Wisdom.
This strong noun, dated back to the 1500′s, has all the possible origins to stand for its meaning. The Old French word sagacite as well as the Latin sagacitatem stand for the quality of being acute. Sagax means ‘of quick perception’ while sagus takes it a step further and represents ‘prophetic’. The Proto Indo European root of sag meant to track down, to trace or to seek. And the 17th and 18th centuries, the Old English secan was used in describing animals with an acute sense of smell.
Why this word?
I feel comfortable saying that all human beings lack sagacity to a certain degree. We may be wise, rightful, just and honest, but only few of us, in any, encompass all four. This word hints us of this possibility- being sagacious is an option. All we have to do is chose it.
How to use sagacity?
Sagacity is a noun; its related adjective is sagacious. Before addressing the ‘how to use it’, let me first of all say- use it!
You could say that a politician is of great sagacity (although usually it would be more correct to say that he lack sagacity). Any verdict can be sagacious, even though in many cases it isn’t.